PROJECT SUMMARY ? Project 3 Parkinson?s disease (PD) is a progressive neurodegenerative disorder characterized by aggregation of the ?- synuclein (?-syn) protein into intracellular inclusions called Lewy bodies (LB) and Lewy neurites (LN). PD presents with both motor and non-motor symptoms. Loss of substantia nigra pars compacta dopamine (DA) neurons and dystrophic striatal projections account for the motor symptoms of PD including a rest tremor, slowness of movement, rigidity, and postural instability. Other neuronal systems affected by pathologic ?-syn contribute to the non-motor symptoms of PD including anxiety, depression, sleep disorders, autonomic dysfunction, constipation, and cognitive impairment. We have compelling evidence that parthanatos contributes to loss of substantia nigra pars compacta DA neurons. However, what role it may play in the general global neurodegeneration suffered in PD has yet to be determined. Together the investigators in this program have developed a new model of ?-synucleinopathy that mimics the stereotypical spread of pathologic ?-syn in the human condition of PD. In the new gut-brain model we will evaluate roles for the c-Abl substrate AIMP2, its activation of PARP1 and parthanatos and the role of the nuclease MIF in the gut peripheral nervous system and in synaptically connected central nervous system regions that contribute to both the motor and non-motor symptoms of PD. Through serum LCAM1+ exosome analysis we will evaluate the utility of phospho- AIMP2 and PAR as disease biomarkers and possible theragnostic markers. Using single nuclei sequencing in the mouse gut-brain model of PD and in PD postmortem tissue coupled with advanced bioinformatic analysis we will explore new signaling networks important in neural dysfunction and degeneration. This investigation will broaden our understanding of the pathogenicity of misfolded ?-syn and will hopefully lead to a new therapeutic intervention for PD. Additionally, this work will provide a new animal model of ?-syn transmission that can be used for testing the effect of a variety of disease-modifying therapeutics